Method for transmitting uplink control channel in wireless communication system and device therefor

ABSTRACT

A method for transmitting an uplink control channel for a terminal configured to support multiple transmission time interval (TTI) lengths in a wireless communication system according to an embodiment of the present invention is performed by the terminal and may comprises the steps of: receiving a first physical downlink shared channel (PDSCH) according to a first TTI length at a first time point; receiving a second PDSCH according to a second TTI length differing from the first TTI length at a second time point; and when TTIs for transmitting uplink control channels for the received first PDSCH and second PDSCH overlap, transmitting uplink control information for the first PDSCH and second PDSCH on a physical uplink control channel (PUCCH) having the shorter TTI length among the first TTI length and the second TTI length.

This application is a continuation of U.S. patent application Ser. No.15/766,554, filed on Apr. 6, 2018, which is a National Stage Applicationof International Application No. PCT/KR2016/012146, filed on Oct. 27,2016, which claims the benefit of U.S. Provisional Application No.62/250,439, filed on Nov. 3, 2015, all of which are hereby incorporatedby reference in their entirety for all purposes as if fully set forthherein.

TECHNICAL FIELD

The present invention relates to a wireless communication system, andmore particularly, to a method of transmitting an uplink control channelin a wireless communication system and an apparatus therefor.

BACKGROUND ART

In a wireless cellular communication system, discussion on a method ofperforming transmission and reception capable of reducing latency asmuch as possible by transmitting data as soon as possible during a shorttime period using a short TTI (transmission time interval) for aservice/UE sensitive to latency and transmitting a response within shorttime in response to the data is in progress. On the contrary, it maytransmit and receive data using a longer TTI for a service/UE lesssensitive to the latency. For a service/UE sensitive to power efficiencyrather than the latency, it may repetitively transmit data with the samelower power or transmit data using a lengthened TTI. The presentinvention proposes a method of transmitting control information and adata signal for enabling the abovementioned operation and a multiplexingmethod.

DISCLOSURE OF THE INVENTION Technical Task

A technical task of the present invention is to provide a method oftransmitting an uplink control channel in a wireless communicationsystem and an operation related to the method.

Technical tasks obtainable from the present invention are non-limitedthe above-mentioned technical task. And, other unmentioned technicaltasks can be clearly understood from the following description by thosehaving ordinary skill in the technical field to which the presentinvention pertains.

Technical Solution

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, accordingto one embodiment, a method of transmitting an uplink control channelfor a terminal configured to support multiple TTI (transmission timeinterval) lengths in a wireless communication system, includes receivinga first PDSCH (physical downlink shared channel) based on a first TTIlength at first timing, receiving a second PDSCH based on a second TTIlength different from the first TTI length at second timing, and when aTTI for transmitting an uplink control channel for the received firstPDSCH is overlapped with a TTI for transmitting an uplink controlchannel for the second PDSCH, transmitting uplink control informationfor the first PDSCH and the second PDSCH on a PUCCH (physical uplinkcontrol channel) having a shorter TTI length among the first TTI lengthand the second TTI length.

Additionally or alternatively, the PUCCH may be transmitted in a shorterTTI among TTIs for transmitting an uplink control channel for the firstPDSCH or the second PDSCH.

Additionally or alternatively, the PUCCH may be transmitted in a TTI fortransmitting a predetermined uplink control channel.

Additionally or alternatively, when a TTI for transmitting an uplinkcontrol channel for a third PDSCH is overlapped with the TTI fortransmitting the uplink control channel for the first PDSCH and thesecond PDSCH, the method may further include transmitting an uplinkcontrol channel for a PDSCH based on a longest TTI among the firstPDSCH, the second PDSCH, and the third PDSCH or a PDSCH based on a TTIlength having a length of 1 ms in a TTI for transmitting a predetermineduplink control channel.

Additionally or alternatively, the PUCCH may be linked to a CCE (controlchannel element) index of a PDCCH (physical downlink control channel)that schedules a PDSCH based on a shorter TTI length among the first TTIlength and the second TTI length or can be determined by the CCE index.

Additionally or alternatively, the PUCCH can be indicated by a PDCCHthat schedules a PDSCH based on a shorter TTI length among the first TTIlength and the second TTI length among a plurality of predeterminedPUCCHs.

Additionally or alternatively, when the TTI for transmitting the uplinkcontrol channel for the first PDSCH is overlapped with the TTI fortransmitting the uplink control channel for the second PDSCH, the uplinkcontrol information for the first PDSCH and the second PDSCH can betransmitted by one selected from the group consisting of a channelselection method, a new PUCCH format, and bundling.

Additionally or alternatively, when hopping of the PUCCH is not allowedwithin a TTI corresponding to the shorter TTI length, the method mayfurther include receiving a configuration on whether or not a repetitivetransmission of the PUCCH is allowed.

Additionally or alternatively, when the repetitive transmission of thePUCCH is allowed, the method may further include receiving configurationinformation including at least one selected from the group consisting ofa TTI in which a repetition part of the PUCCH is transmitted, a TTIsection during which the repetition part of the PUCCH is transmitted, anuplink resource in which the repetition part of the PUCCH istransmitted, and criteria for determining an uplink resource in whichthe repetition part of the PUCCH is transmitted.

To further achieve these and other advantages and in accordance with thepurpose of the present invention, according to a different embodiment, aterminal configured to support multiple TTI (transmission time interval)lengths in a wireless communication system includes a transmitter and areceiver, and a processor that controls the transmitter and thereceiver, the processor receives a first PDSCH (physical downlink sharedchannel) based on a first TTI length at first timing, receives a secondPDSCH based on a second TTI length different from the first TTI lengthat second timing, when a TTI for transmitting an uplink control channelfor the received first PDSCH is overlapped with a TTI for transmittingan uplink control channel for the second PDSCH, transmits uplink controlinformation for the first PDSCH and the second PDSCH on a PUCCH(physical uplink control channel) having a shorter TTI length among thefirst TTI length and the second TTI length.

Additionally or alternatively, the PUCCH may be transmitted in a shorterTTI among TTIs for transmitting an uplink control channel for the firstPDSCH or the second PDSCH.

Additionally or alternatively, the PUCCH can be transmitted in a TTI fortransmitting a predetermined uplink control channel.

Additionally or alternatively, when a TTI for transmitting an uplinkcontrol channel for a third PDSCH is overlapped with the TTI fortransmitting the uplink control channel for the first PDSCH and thesecond PDSCH, the processor may transmit an uplink control channel for aPDSCH based on a longest TTI among the first PDSCH, the second PDSCH,and the third PDSCH or a PDSCH according to a TTI length having a lengthof 1 ms in a TTI for transmitting a predetermined uplink controlchannel.

Additionally or alternatively, the PUCCH may be linked to a CCE (controlchannel element) index of a PDCCH (physical downlink control channel)that schedules a PDSCH based on a shorter TTI length among the first TTIlength and the second TTI length or can be determined by the CCE index.

Additionally or alternatively, the PUCCH may be indicated by a PDCCHthat schedules a PDSCH based on a shorter TTI length among the first TTIlength and the second TTI length among a plurality of predeterminedPUCCHs.

Additionally or alternatively, when the TTI for transmitting the uplinkcontrol channel for the first PDSCH is overlapped with the TTI fortransmitting the uplink control channel for the second PDSCH, the uplinkcontrol information for the first PDSCH and the second PDSCH may betransmitted by one selected from the group consisting of a channelselection method, a new PUCCH format, and bundling.

Additionally or alternatively, when hopping of the PUCCH is not allowedwithin a length of the shorter TTI, the processor may receive aconfiguration on whether or not a repetitive transmission of the PUCCHis allowed.

Additionally or alternatively, when the repetitive transmission of thePUCCH is allowed, the processor may receive configuration informationincluding at least one selected from the group consisting of a TTI atwhich a repetition part of the PUCCH is transmitted, a TTI sectionduring which the repetition part of the PUCCH is transmitted, an uplinkresource in which the repetition part of the PUCCH is transmitted, andcriteria for determining an uplink resource in which the repetition partof the PUCCH is transmitted.

Technical solutions obtainable from the present invention arenon-limited the above-mentioned technical solutions. And, otherunmentioned technical solutions can be clearly understood from thefollowing description by those having ordinary skill in the technicalfield to which the present invention pertains.

Advantageous Effects

According to one embodiment of the present invention, it is able toefficiently transmit and receive an uplink control channel in a wirelesscommunication system.

Effects obtainable from the present invention may be non-limited by theabove mentioned effect. And, other unmentioned effects can be clearlyunderstood from the following description by those having ordinary skillin the technical field to which the present invention pertains.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a diagram for an example of a radio frame structure used in awireless communication system;

FIG. 2 is a diagram for an example of a downlink (DL)/uplink (UL) slotstructure in a wireless communication system;

FIG. 3 is a diagram for an example of a downlink (DL) subframe structureused in 3GPP LTE/LTE-A system;

FIG. 4 is a diagram for an example of an uplink (UL) subframe structureused in 3GPP LTE/LTE-A system;

FIG. 5 is a diagram illustrating DL reception timing and UL transmissiontiming of UEs operating with a different TTI (transmission timeinterval);

FIG. 6 is a diagram illustrating an example of processing a case thattransmission timing of HARQ ACK/NACK feedback of a different TTI(transmission time interval) is overlapped according to one embodimentof the present invention;

FIG. 7 is a diagram illustrating an example of processing a case thattransmission timing of HARQ ACK/NACK feedback of a different TTI(transmission time interval) is overlapped according to one embodimentof the present invention;

FIG. 8 is a diagram illustrating an example of processing a case thattransmission timing of HARQ ACK/NACK feedback of a different TTI(transmission time interval) is overlapped according to one embodimentof the present invention;

FIG. 9 is a diagram illustrating an example of processing a case thattransmission of a repeated part of HARQ ACK/NACK feedback is collidedwith a different HARQ ACK/NACK feedback according to one embodiment ofthe present invention;

FIG. 10 is a flowchart for an operation according to one embodiment ofthe present invention;

FIG. 11 is a block diagram of a device for implementing embodiment(s) ofthe present invention.

BEST MODE Mode for Invention

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The accompanying drawings illustrate exemplary embodiments ofthe present invention and provide a more detailed description of thepresent invention. However, the scope of the present invention shouldnot be limited thereto.

In some cases, to prevent the concept of the present invention frombeing ambiguous, structures and apparatuses of the known art will beomitted, or will be shown in the form of a block diagram based on mainfunctions of each structure and apparatus. Also, wherever possible, thesame reference numbers will be used throughout the drawings and thespecification to refer to the same or like parts.

In the present invention, a user equipment (UE) is fixed or mobile. TheUE is a device that transmits and receives user data and/or controlinformation by communicating with a base station (BS). The term ‘UE’ maybe replaced with ‘terminal equipment’, ‘Mobile Station (MS)’, ‘MobileTerminal (MT)’, ‘User Terminal (UT)’, ‘Subscriber Station (SS)’,‘wireless device’, ‘Personal Digital Assistant (PDA)’, ‘wireless modem’,‘handheld device’, etc. A BS is typically a fixed station thatcommunicates with a UE and/or another BS. The BS exchanges data andcontrol information with a UE and another BS. The term ‘BS’ may bereplaced with ‘Advanced Base Station (ABS)’, ‘Node B’, ‘evolved-Node B(eNB)’, ‘Base Transceiver System (BTS)’, ‘Access Point (AP)’,‘Processing Server (PS)’, etc. In the following description, BS iscommonly called eNB.

In the present invention, a node refers to a fixed point capable oftransmitting/receiving a radio signal to/from a UE by communication withthe UE. Various eNBs can be used as nodes. For example, a node can be aBS, NB, eNB, pico-cell eNB (PeNB), home eNB (HeNB), relay, repeater,etc. Furthermore, a node may not be an eNB. For example, a node can be aradio remote head (RRH) or a radio remote unit (RRU). The RRH and RRUhave power levels lower than that of the eNB. Since the RRH or RRU(referred to as RRH/RRU hereinafter) is connected to an eNB through adedicated line such as an optical cable in general, cooperativecommunication according to RRH/RRU and eNB can be smoothly performedcompared to cooperative communication according to eNBs connectedthrough a wireless link. At least one antenna is installed per node. Anantenna may refer to an antenna port, a virtual antenna or an antennagroup. A node may also be called a point. Unlike a conventionalcentralized antenna system (CAS) (i.e. single node system) in whichantennas are concentrated in an eNB and controlled an eNB controller,plural nodes are spaced apart at a predetermined distance or longer in amulti-node system. The plural nodes can be managed by one or more eNBsor eNB controllers that control operations of the nodes or schedule datato be transmitted/received through the nodes. Each node may be connectedto an eNB or eNB controller managing the corresponding node via a cableor a dedicated line. In the multi-node system, the same cell identity(ID) or different cell IDs may be used for signal transmission/receptionthrough plural nodes. When plural nodes have the same cell ID, each ofthe plural nodes operates as an antenna group of a cell. If nodes havedifferent cell IDs in the multi-node system, the multi-node system canbe regarded as a multi-cell (e.g., macro-cell/femto-cell/pico-cell)system. When multiple cells respectively configured by plural nodes areoverlaid according to coverage, a network configured by multiple cellsis called a multi-tier network. The cell ID of the RRH/RRU may beidentical to or different from the cell ID of an eNB. When the RRH/RRUand eNB use different cell IDs, both the RRH/RRU and eNB operate asindependent eNBs.

In a multi-node system according to the present invention, which will bedescribed below, one or more eNBs or eNB controllers connected to pluralnodes can control the plural nodes such that signals are simultaneouslytransmitted to or received from a UE through some or all nodes. Whilethere is a difference between multi-node systems according to the natureof each node and implementation form of each node, multi-node systemsare discriminated from single node systems (e.g. CAS, conventional MIMOsystems, conventional relay systems, conventional repeater systems,etc.) since a plurality of nodes provides communication services to a UEin a predetermined time-frequency resource. Accordingly, embodiments ofthe present invention with respect to a method of performing coordinateddata transmission using some or all nodes can be applied to varioustypes of multi-node systems. For example, a node refers to an antennagroup spaced apart from another node by a predetermined distance ormore, in general. However, embodiments of the present invention, whichwill be described below, can even be applied to a case in which a noderefers to an arbitrary antenna group irrespective of node interval. Inthe case of an eNB including an X-pole (cross polarized) antenna, forexample, the embodiments of the preset invention are applicable on theassumption that the eNB controls a node composed of an H-pole antennaand a V-pole antenna.

A communication scheme through which signals are transmitted/receivedvia plural transmit (Tx)/receive (Rx) nodes, signals aretransmitted/received via at least one node selected from plural Tx/Rxnodes, or a node transmitting a downlink signal is discriminated from anode transmitting an uplink signal is called multi-eNB MIMO or CoMP(Coordinated Multi-Point Tx/Rx). Coordinated transmission schemes fromamong CoMP communication schemes can be categorized into JP (JointProcessing) and scheduling coordination. The former may be divided intoJT (Joint Transmission)/JR (Joint Reception) and DPS (Dynamic PointSelection) and the latter may be divided into CS (CoordinatedScheduling) and CB (Coordinated Beamforming). DPS may be called DCS(Dynamic Cell Selection). When JP is performed, more variouscommunication environments can be generated, compared to other CoMPschemes. JT refers to a communication scheme by which plural nodestransmit the same stream to a UE and JR refers to a communication schemeby which plural nodes receive the same stream from the UE. The UE/eNBcombine signals received from the plural nodes to restore the stream. Inthe case of JT/JR, signal transmission reliability can be improvedaccording to transmit diversity since the same stream is transmittedfrom/to plural nodes. DPS refers to a communication scheme by which asignal is transmitted/received through a node selected from plural nodesaccording to a specific rule. In the case of DPS, signal transmissionreliability can be improved because a node having a good channel statebetween the node and a UE is selected as a communication node.

In the present invention, a cell refers to a specific geographical areain which one or more nodes provide communication services. Accordingly,communication with a specific cell may mean communication with an eNB ora node providing communication services to the specific cell. Adownlink/uplink signal of a specific cell refers to a downlink/uplinksignal from/to an eNB or a node providing communication services to thespecific cell. A cell providing uplink/downlink communication servicesto a UE is called a serving cell. Furthermore, channel status/quality ofa specific cell refers to channel status/quality of a channel or acommunication link generated between an eNB or a node providingcommunication services to the specific cell and a UE. In 3GPP LTE-Asystems, a UE can measure downlink channel state from a specific nodeusing one or more CSI-RSs (Channel State Information Reference Signals)transmitted through antenna port(s) of the specific node on a CSI-RSresource allocated to the specific node. In general, neighboring nodestransmit CSI-RS resources on orthogonal CSI-RS resources. When CSI-RSresources are orthogonal, this means that the CSI-RS resources havedifferent subframe configurations and/or CSI-RS sequences which specifysubframes to which CSI-RSs are allocated according to CSI-RS resourceconfigurations, subframe offsets and transmission periods, etc. whichspecify symbols and subcarriers carrying the CSI RSs.

In the present invention, PDCCH (Physical Downlink ControlChannel)/PCFICH (Physical Control Format Indicator Channel)/PHICH(Physical Hybrid automatic repeat request Indicator Channel)/PDSCH(Physical Downlink Shared Channel) refer to a set of time-frequencyresources or resource elements respectively carrying DCI (DownlinkControl Information)/CFI (Control Format Indicator)/downlink ACK/NACK(Acknowledgement/Negative ACK)/downlink data. In addition, PUCCH(Physical Uplink Control Channel)/PUSCH (Physical Uplink SharedChannel)/PRACH (Physical Random Access Channel) refer to sets oftime-frequency resources or resource elements respectively carrying UCI(Uplink Control Information)/uplink data/random access signals. In thepresent invention, a time-frequency resource or a resource element (RE),which is allocated to or belongs toPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH, is referred to as aPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH RE orPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH resource. In the followingdescription, transmission of PUCCH/PUSCH/PRACH by a UE is equivalent totransmission of uplink control information/uplink data/random accesssignal through or on PUCCH/PUSCH/PRACH. Furthermore, transmission ofPDCCH/PCFICH/PHICH/PDSCH by an eNB is equivalent to transmission ofdownlink data/control information through or onPDCCH/PCFICH/PHICH/PDSCH.

FIG. 1 illustrates an exemplary radio frame structure used in a wirelesscommunication system. FIG. 1(a) illustrates a frame structure forfrequency division duplex (FDD) used in 3GPP LTE/LTE-A and FIG. 1(b)illustrates a frame structure for time division duplex (TDD) used in3GPP LTE/LTE-A.

Referring to FIG. 1, a radio frame used in 3GPP LTE/LTE-A has a lengthof 10 ms (307200 Ts) and includes 10 subframes in equal size. The 10subframes in the radio frame may be numbered. Here, Ts denotes samplingtime and is represented as Ts=1/(2048*15 kHz). Each subframe has alength of 1 ms and includes two slots. 20 slots in the radio frame canbe sequentially numbered from 0 to 19. Each slot has a length of 0.5 ms.A time for transmitting a subframe is defined as a transmission timeinterval (TTI). Time resources can be discriminated by a radio framenumber (or radio frame index), subframe number (or subframe index) and aslot number (or slot index).

The radio frame can be configured differently according to duplex mode.Downlink transmission is discriminated from uplink transmission byfrequency in FDD mode, and thus the radio frame includes only one of adownlink subframe and an uplink subframe in a specific frequency band.In TDD mode, downlink transmission is discriminated from uplinktransmission by time, and thus the radio frame includes both a downlinksubframe and an uplink subframe in a specific frequency band.

Table 1 shows DL-UL configurations of subframes in a radio frame in theTDD mode.

TABLE 1 Downlink-to- DL-UL Uplink config- Switch-point Subframe numberuration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S U U U 1 5ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms  D S U U U D DD D D 4 10 ms  D S U U D D D D D D 5 10 ms  D S U D D D D D D D 6 5 ms DS U U U D S U U D

In Table 1, D denotes a downlink subframe, U denotes an uplink subframeand S denotes a special subframe. The special subframe includes threefields of DwPTS (Downlink Pilot TimeSlot), GP (Guard Period), and UpPTS(Uplink Pilot TimeSlot). DwPTS is a period reserved for downlinktransmission and UpPTS is a period reserved for uplink transmission.Table 2 shows special subframe configuration.

TABLE 2 Normal cyclic prefix in downlink Extended cyclic prefix indownlink UpPTS UpPTS Special Normal Extended Normal Extended subframecyclic prefix cyclic prefix cyclic prefix cyclic prefix configurationDwPTS in uplink in uplink DwPTS in uplink in uplink 0  6592 · T_(s) 2192· T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s) 1 19760 ·T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 · T_(s) 25600· T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 · T_(s) 5  6592· T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 · T_(s) 23040 ·T_(s) 7 21952 · T_(s) 12800 · T_(s) 8 24144 · T_(s) — — — 9 13168 ·T_(s) — — —

FIG. 2 illustrates an exemplary downlink/uplink slot structure in awireless communication system. Particularly, FIG. 2 illustrates aresource grid structure in 3GPP LTE/LTE-A. A resource grid is presentper antenna port.

Referring to FIG. 2, a slot includes a plurality of OFDM (OrthogonalFrequency Division Multiplexing) symbols in the time domain and aplurality of resource blocks (RBs) in the frequency domain. An OFDMsymbol may refer to a symbol period. A signal transmitted in each slotmay be represented by a resource grid composed of N_(RB) ^(DL/UL)*N_(sc)^(RB) subcarriers and N_(symb) ^(DL/UL) symb OFDM symbols. Here, RBN_(RB) ^(DL) denotes the number of RBs in a downlink slot and N_(RB)^(UL) RB denotes the number of RBs in an uplink slot. N_(RB) ^(DL) andN_(RB) ^(UL) respectively depend on a DL transmission bandwidth and a ULtransmission bandwidth. N_(symb) ^(DL) denotes the number of OFDMsymbols in the downlink slot and N_(symb) ^(UL) denotes the number ofOFDM symbols in the uplink slot. In addition, N_(sc) ^(RB) denotes thenumber of subcarriers constructing one RB.

An OFDM symbol may be called an SC-FDM (Single Carrier FrequencyDivision Multiplexing) symbol according to multiple access scheme. Thenumber of OFDM symbols included in a slot may depend on a channelbandwidth and the length of a cyclic prefix (CP). For example, a slotincludes OFDM symbols in the case of normal CP and 6 OFDM symbols in thecase of extended CP. While FIG. 2 illustrates a subframe in which a slotincludes 7 OFDM symbols for convenience, embodiments of the presentinvention can be equally applied to subframes having different numbersof OFDM symbols. Referring to FIG. 2, each OFDM symbol includes N_(RB)^(DL/UL)*N_(sc) ^(RB) subcarriers in the frequency domain. Subcarriertypes can be classified into a data subcarrier for data transmission, areference signal subcarrier for reference signal transmission, and nullsubcarriers for a guard band and a direct current (DC) component. Thenull subcarrier for a DC component is a subcarrier remaining unused andis mapped to a carrier frequency (f0) during OFDM signal generation orfrequency up-conversion. The carrier frequency is also called a centerfrequency.

An RB is defined by N_(symb) ^(DL/UL) (e.g., 7) consecutive OFDM symbolsin the time domain and N_(sc) ^(RB) (e.g., 12) consecutive subcarriersin the frequency domain. For reference, a resource composed by an OFDMsymbol and a subcarrier is called a resource element (RE) or a tone.Accordingly, an RB is composed of symb N_(RB) ^(DL/UL)*N_(sc) ^(RB) REs.Each RE in a resource grid can be uniquely defined by an index pair(k, 1) in a slot. Here, k is an index in the range of 0 to N_(symb)^(DL/UL)*N_(sc) ^(RB)−1 in the frequency domain and 1 is an index in therange of 0 to symb N_(symb) ^(DL/UL)−1.

Two RBs that occupy N_(sc) ^(RB) consecutive subcarriers in a subframeand respectively disposed in two slots of the subframe are called aphysical resource block (PRB) pair. Two RBs constituting a PRB pair havethe same PRB number (or PRB index). A virtual resource block (VRB) is alogical resource allocation unit for resource allocation. The VRB hasthe same size as that of the PRB. The VRB may be divided into alocalized VRB and a distributed VRB depending on a mapping scheme of VRBinto PRB. The localized VRBs are mapped into the PRBs, whereby VRBnumber (VRB index) corresponds to PRB number. That is, nPRB=nVRB isobtained. Numbers are given to the localized VRBs from 0 to N_(VRB)^(DL)−1, and N_(VRB) ^(DL)=N_(RB) ^(DL) is obtained. Accordingly,according to the localized mapping scheme, the VRBs having the same VRBnumber are mapped into the PRBs having the same PRB number at the firstslot and the second slot. On the other hand, the distributed VRBs aremapped into the PRBs through interleaving. Accordingly, the VRBs havingthe same VRB number may be mapped into the PRBs having different PRBnumbers at the first slot and the second slot. Two PRBs, which arerespectively located at two slots of the subframe and have the same VRBnumber, will be referred to as a pair of VRBs.

FIG. 3 illustrates a downlink (DL) subframe structure used in 3GPPLTE/LTE-A.

Referring to FIG. 3, a DL subframe is divided into a control region anda data region. A maximum of three (four) OFDM symbols located in a frontportion of a first slot within a subframe correspond to the controlregion to which a control channel is allocated. A resource regionavailable for PDCCH transmission in the DL subframe is referred to as aPDCCH region hereinafter. The remaining OFDM symbols correspond to thedata region to which a physical downlink shared chancel (PDSCH) isallocated. A resource region available for PDSCH transmission in the DLsubframe is referred to as a PDSCH region hereinafter. Examples ofdownlink control channels used in 3GPP LTE include a physical controlformat indicator channel (PCFICH), a physical downlink control channel(PDCCH), a physical hybrid ARQ indicator channel (PHICH), etc. ThePCFICH is transmitted at a first OFDM symbol of a subframe and carriesinformation regarding the number of OFDM symbols used for transmissionof control channels within the subframe. The PHICH is a response ofuplink transmission and carries an HARQ acknowledgment (ACK)/negativeacknowledgment (NACK) signal.

Control information carried on the PDCCH is called downlink controlinformation (DCI). The DCI contains resource allocation information andcontrol information for a UE or a UE group. For example, the DCIincludes a transport format and resource allocation information of adownlink shared channel (DL-SCH), a transport format and resourceallocation information of an uplink shared channel (UL-SCH), paginginformation of a paging channel (PCH), system information on the DL-SCH,information about resource allocation of an upper layer control messagesuch as a random access response transmitted on the PDSCH, a transmitcontrol command set with respect to individual UEs in a UE group, atransmit power control command, information on activation of a voiceover IP (VoIP), downlink assignment index (DAI), etc. The transportformat and resource allocation information of the DL-SCH are also calledDL scheduling information or a DL grant and the transport format andresource allocation information of the UL-SCH are also called ULscheduling information or a UL grant. The size and purpose of DCIcarried on a PDCCH depend on DCI format and the size thereof may bevaried according to coding rate. Various formats, for example, formats 0and 4 for uplink and formats 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C, 3 and 3Afor downlink, have been defined in 3GPP LTE. Control information such asa hopping flag, information on RB allocation, modulation coding scheme(MCS), redundancy version (RV), new data indicator (NDI), information ontransmit power control (TPC), cyclic shift demodulation reference signal(DMRS), UL index, channel quality information (CQI) request, DLassignment index, HARQ process number, transmitted precoding matrixindicator (TPMI), precoding matrix indicator (PMI), etc. is selected andcombined based on DCI format and transmitted to a UE as DCI.

In general, a DCI format for a UE depends on transmission mode (TM) setfor the UE. In other words, only a DCI format corresponding to aspecific TM can be used for a UE configured in the specific TM.

A PDCCH is transmitted on an aggregation of one or several consecutivecontrol channel elements (CCEs). The CCE is a logical allocation unitused to provide the PDCCH with a coding rate based on a state of a radiochannel. The CCE corresponds to a plurality of resource element groups(REGs). For example, a CCE corresponds to 9 REGs and an REG correspondsto 4 REs. 3GPP LTE defines a CCE set in which a PDCCH can be located foreach UE. A CCE set from which a UE can detect a PDCCH thereof is calleda PDCCH search space, simply, search space. An individual resourcethrough which the PDCCH can be transmitted within the search space iscalled a PDCCH candidate. A set of PDCCH candidates to be monitored bythe UE is defined as the search space. In 3GPP LTE/LTE-A, search spacesfor DCI formats may have different sizes and include a dedicated searchspace and a common search space. The dedicated search space is aUE-specific search space and is configured for each UE. The commonsearch space is configured for a plurality of UEs. Aggregation levelsdefining the search space is as follows.

TABLE 3 Search Space Aggregation Size Number of PDCCH Type Level L [inCCEs] candidates M(L) UE-specific 1 6 6 2 12 6 4 8 2 8 16 2 Common 4 164 8 16 2

A PDCCH candidate corresponds to 1, 2, 4 or 8 CCEs according to CCEaggregation level. An eNB transmits a PDCCH (DCI) on an arbitrary PDCCHcandidate with in a search space and a UE monitors the search space todetect the PDCCH (DCI). Here, monitoring refers to attempting to decodeeach PDCCH in the corresponding search space according to all monitoredDCI formats. The UE can detect the PDCCH thereof by monitoring pluralPDCCHs. Since the UE does not know the position in which the PDCCHthereof is transmitted, the UE attempts to decode all PDCCHs of thecorresponding DCI format for each subframe until a PDCCH having the IDthereof is detected. This process is called blind detection (or blinddecoding (BD)).

The eNB can transmit data for a UE or a UE group through the dataregion. Data transmitted through the data region may be called userdata. For transmission of the user data, a physical downlink sharedchannel (PDSCH) may be allocated to the data region. A paging channel(PCH) and downlink-shared channel (DL-SCH) are transmitted through thePDSCH. The UE can read data transmitted through the PDSCH by decodingcontrol information transmitted through a PDCCH. Informationrepresenting a UE or a UE group to which data on the PDSCH istransmitted, how the UE or UE group receives and decodes the PDSCH data,etc. is included in the PDCCH and transmitted. For example, if aspecific PDCCH is CRC (cyclic redundancy check)-masked having radionetwork temporary identify (RNTI) of “A” and information about datatransmitted using a radio resource (e.g., frequency position) of “B” andtransmission format information (e.g., transport block size, modulationscheme, coding information, etc.) of “C” is transmitted through aspecific DL subframe, the UE monitors PDCCHs using RNTI information anda UE having the RNTI of “A” detects a PDCCH and receives a PDSCHindicated by “B” and “C” using information about the PDCCH.

A reference signal (RS) to be compared with a data signal is necessaryfor the UE to demodulate a signal received from the eNB. A referencesignal refers to a predetermined signal having a specific waveform,which is transmitted from the eNB to the UE or from the UE to the eNBand known to both the eNB and UE. The reference signal is also called apilot. Reference signals are categorized into a cell-specific RS sharedby all UEs in a cell and a modulation RS (DM RS) dedicated for aspecific UE. A DM RS transmitted by the eNB for demodulation of downlinkdata for a specific UE is called a UE-specific RS. Both or one of DM RSand CRS may be transmitted on downlink. When only the DM RS istransmitted without CRS, an RS for channel measurement needs to beadditionally provided because the DM RS transmitted using the sameprecoder as used for data can be used for demodulation only. Forexample, in 3GPP LTE(-A), CSI-RS corresponding to an additional RS formeasurement is transmitted to the UE such that the UE can measurechannel state information. CSI-RS is transmitted in each transmissionperiod corresponding to a plurality of subframes based on the fact thatchannel state variation with time is not large, unlike CRS transmittedper subframe.

FIG. 4 illustrates an exemplary uplink subframe structure used in 3GPPLTE/LTE-A.

Referring to FIG. 4, a UL subframe can be divided into a control regionand a data region in the frequency domain. One or more PUCCHs (physicaluplink control channels) can be allocated to the control region to carryuplink control information (UCI). One or more PUSCHs (Physical uplinkshared channels) may be allocated to the data region of the UL subframeto carry user data.

In the UL subframe, subcarriers spaced apart from a DC subcarrier areused as the control region. In other words, subcarriers corresponding toboth ends of a UL transmission bandwidth are assigned to UCItransmission. The DC subcarrier is a component remaining unused forsignal transmission and is mapped to the carrier frequency f0 duringfrequency up-conversion. A PUCCH for a UE is allocated to an RB pairbelonging to resources operating at a carrier frequency and RBsbelonging to the RB pair occupy different subcarriers in two slots.Assignment of the PUCCH in this manner is represented as frequencyhopping of an RB pair allocated to the PUCCH at a slot boundary. Whenfrequency hopping is not applied, the RB pair occupies the samesubcarrier.

The PUCCH can be used to transmit the following control information.

-   -   Scheduling Request (SR): This is information used to request a        UL-SCH resource and is transmitted using On-Off Keying (OOK)        scheme.    -   HARQ ACK/NACK: This is a response signal to a downlink data        packet on a PDSCH and indicates whether the downlink data packet        has been successfully received. A 1-bit ACK/NACK signal is        transmitted as a response to a single downlink codeword and a        2-bit ACK/NACK signal is transmitted as a response to two        downlink codewords. HARQ-ACK responses include positive ACK        (ACK), negative ACK (NACK), discontinuous transmission (DTX) and        NACK/DTX. Here, the term HARQ-ACK is used interchangeably with        the term HARQ ACK/NACK and ACK/NACK.    -   Channel State Indicator (CSI): This is feedback information        about a downlink channel. Feedback information regarding MIMO        includes a rank indicator (RI) and a precoding matrix indicator        (PMI).

The quantity of control information (UCI) that a UE can transmit througha subframe depends on the number of SC-FDMA symbols available forcontrol information transmission. The SC-FDMA symbols available forcontrol information transmission correspond to SC-FDMA symbols otherthan SC-FDMA symbols of the subframe, which are used for referencesignal transmission. In the case of a subframe in which a soundingreference signal (SRS) is configured, the last SC-FDMA symbol of thesubframe is excluded from the SC-FDMA symbols available for controlinformation transmission. A reference signal is used to detect coherenceof the PUCCH. The PUCCH supports various formats according toinformation transmitted thereon.

Table 4 shows the mapping relationship between PUCCH formats and UCI inLTE/LTE-A.

TABLE 4 Number of bits per PUCCH Modulation subframe, format schemeM_(bit) Usage Etc. 1 N/A N/A SR (Scheduling Request) 1a BPSK 1 ACK/NACKor One SR + ACK/NACK codeword 1b QPSK 2 ACK/NACK or Two SR + ACK/NACKcodeword 2 QPSK 20 CQI/PMI/RI Joint coding ACK/NACK (extended CP) 2aQPSK + 21 CQI/PMI/RI + Normal CP BPSK ACK/NACK only 2b QPSK + 22CQI/PMI/RI + Normal CP QPSK ACK/NACK only 3 QPSK 48 ACK/NACK or SR +ACK/NACK or CQI/PMI/RI + ACK/NACK

Referring to Table 4, PUCCH formats 1/1a/1b are used to transmitACK/NACK information, PUCCH format 2/2a/2b are used to carry CSI such asCQI/PMI/RI and PUCCH format 3 is used to transmit ACK/NACK information.

CSI Reporting

In the 3GPP LTE(-A) system, a user equipment (UE) is defined to reportCSI to a BS. Herein, the CSI collectively refers to informationindicating the quality of a radio channel (also called a link) createdbetween a UE and an antenna port. The CSI includes, for example, a rankindicator (RI), a precoding matrix indicator (PMI), and a channelquality indicator (CQI). Herein, the RI, which indicates rankinformation about a channel, refers to the number of streams that a UEreceives through the same time-frequency resource. The RI value isdetermined depending on long-term fading of the channel, and is thususually fed back to the BS by the UE with a longer period than for thePMI and CQI. The PMI, which has a value reflecting the channel spaceproperty, indicates a precoding index preferred by the UE based on ametric such as SINR. The CQI, which has a value indicating the intensityof a channel, typically refers to a receive SINR which may be obtainedby the BS when the PMI is used.

The UE calculates, based on measurement of the radio channel, apreferred PMI and RI from which an optimum or highest transmission ratemay be derived when used by the BS in the current channel state, andfeeds back the calculated PMI and RI to the BS. Herein, the CQI refersto a modulation and coding scheme providing an acceptable packet errorprobability for the PMI/RI that is fed back.

In the LTE-A system which is expected to include more precise MU-MIMOand explicit CoMP operations, current CSI feedback is defined in LTE,and thus new operations to be introduced may not be sufficientlysupported. As requirements for CSI feedback accuracy for obtainingsufficient MU-MIMO or CoMP throughput gain became complicated, it hasbeen agreed that the PMI should be configured with a long term/widebandPMI (W₁) and a short term/subband PMI (W₂). In other words, the finalPMI is expressed as a function of W₁ and W₂. For example, the final PMIW may be defined as follows: W=W₁*W₂ or W=W₂*W₁. Accordingly, in LTE-A,the CSI may include RI, W₁, W₂ and CQI.

In the 3GPP LTE(-A) system, an uplink channel used for CSI transmissionis configured as shown in Table 5.

TABLE 5 Periodic CSI Aperiodic CSI Scheduling scheme transmissiontransmission Frequency non-selective PUCCH — Frequency selective PUCCHPUSCH

Referring to Table 5, CSI may be transmitted with a periodicity definedin a higher layer, using a physical uplink control channel (PUCCH). Whenneeded by the scheduler, a physical uplink shared channel (PUSCH) may beaperiodically used to transmit the CSI. Transmission of the CSI over thePUSCH is possible only in the case of frequency selective scheduling andaperiodic CSI transmission. Hereinafter, CSI transmission schemesaccording to scheduling schemes and periodicity will be described.

1) Transmitting the CQI/PMI/RI Over the PUSCH after Receiving a CSITransmission Request Control Signal (a CSI Request)

A PUSCH scheduling control signal (UL grant) transmitted over a PDCCHmay include a control signal for requesting transmission of CSI. Thetable below shows modes of the UE in which the CQI, PMI and RI aretransmitted over the PUSCH.

TABLE 6 PMI Feedback Type No PMI Single PMI Multiple PMIs PUSCH CQIWideband Mode 1-2 Feedback Type (Wideband CQI) RI 1st wideband CQI(4bit)2nd wideband CQI(4bit) if RI > 1 N*Subband PMI(4bit) (N is the total #of subbands) (if 8Tx Ant, N*subband W2 + wideband W1) UE selected Mode2-0 Mode 2-2 (Subband CQI) RI (only for Open- RI loop SM) 1st wideband1st wideband CQI(4bit) + Best-M CQI(4bit) + Best-M CQI(2bit) CQI(2bit)2nd wideband (Best-M CQI: An CQI(4bit) + Best-M average CQI for MCQI(2bit) if RI > 1 SBs selected from Best-M index (L among N SBs) bit)Best-M index (L Wideband bit) PMI(4bit) + Best-M PMI(4bit) (if 8Tx Ant,wideband W2 + Best-M W2 + wideband W1) Higher Layer- Mode 3-0 Mode 3-1Mode 3-2 configured RI (only for Open- RI RI (Subband CQI) loop SM) 1stwideband 1st wideband 1st wideband CQI(4bit) + CQI(4bit) + CQI(4bit) +N*subbandCQI(2bit) N*subbandCQI(2bit) N*subbandCQI(2bit) 2nd wideband2nd wideband CQI(4bit) + CQI(4bit) + N*subbandCQI(2bit)N*subbandCQI(2bit) if RI > 1 if RI > 1 Wideband N*Subband PMI(4bit)PMI(4bit) (if 8Tx Ant, (N is the total # of wideband W2 + subbands)wideband W1) (if 8Tx Ant, N*subband W2 + wideband W1)

The transmission modes in Table 6 are selected in a higher layer, andthe CQI/PMI/RI are all transmitted in a PUSCH subframe. Hereinafter,uplink transmission methods for the UE according to the respective modeswill be described.

Mode 1-2 represents a case where precoding matrices are selected on theassumption that data is transmitted only in subbands. The UE generates aCQI on the assumption of a precoding matrix selected for a system bandor a whole band (set S) designated in a higher layer. In Mode 1-2, theUE may transmit a CQI and a PMI value for each subband. Herein, the sizeof each subband may depend on the size of the system band.

A UE in Mode 2-0 may select M preferred subbands for a system band or aband (set S) designated in a higher layer. The UE may generate one CQIvalue on the assumption that data is transmitted for the M selectedsubbands. Preferably, the UE additionally reports one CQI (wideband CQI)value for the system band or set S. If there are multiple codewords forthe M selected subbands, the UE defines a CQI value for each codeword ina differential form.

In this case, the differential CQI value is determined as a differencebetween an index corresponding to the CQI value for the M selectedsubbands and a wideband (WB) CQI index.

The UE in Mode 2-0 may transmit, to a BS, information about thepositions of the M selected subbands, one CQI value for the M selectedsubbands and a CQI value generated for the whole band or designated band(set S). Herein, the size of a subband and the value of M may depend onthe size of the system band.

A UE in Mode 2-2 may select positions of M preferred subbands and asingle precoding matrix for the M preferred subbands simultaneously onthe assumption that data is transmitted through the M preferredsubbands. Herein, a CQI value for the M preferred subbands is definedfor each codeword. In addition, the UE additionally generates a widebandCQI value for the system band or a designated band (set S).

The UE in Mode 2-2 may transmit, to the BS, information about thepositions of the M preferred subbands, one CQI value for the M selectedsubbands and a single PMI for the M preferred subbands, a wideband PMI,and a wideband CQI value. Herein, the size of a subband and the value ofM may depend on the size of the system band.

A UE in Mode 3-0 generates a wideband CQI value. The UE generates a CQIvalue for each subband on the assumption that data is transmittedthrough each subband. In this case, even if RI>1, the CQI valuerepresents only the CQI value for the first codeword.

A UE in Mode 3-1 generates a single precoding matrix for the system bandor a designated band (set S). The UE generates a CQI subband for eachcodeword on the assumption of the single precoding matrix generated foreach subband. In addition, the UE may generate a wideband CQI on theassumption of the single precoding matrix. The CQI value for eachsubband may be expressed in a differential form. The subband CQI valueis calculated as a difference between the subband CQI index and thewideband CQI index. Herein, the size of each subband may depend on thesize of the system band.

A UE in Mode 3-2 generates a precoding matrix for each subband in placeof a single precoding matrix for the whole band, in contrast with the UEin Mode 3-1.

2) Periodic CQI/PMI/RI Transmission Over PUCCH

The UE may periodically transmit CSI (e.g., CQI/PMI/PTI (precoding typeindicator) and/or RI information) to the BS over a PUCCH. If the UEreceives a control signal instructing transmission of user data, the UEmay transmit a CQI over the PUCCH. Even if the control signal istransmitted over a PUSCH, the CQI/PMI/PTI/RI may be transmitted in oneof the modes defined in the following table.

TABLE 7 PMI feedback type No PMI Single PMI PUCCH CQI Wideband Mode 1-0Mode 1-1 feedback type (wideband CQI) UE selective Mode 2-0 Mode 2-1(subband CQI)

A UE may be set in transmission modes as shown in Table 7. Referring toTable 7, in Mode 2-0 and Mode 2-1, a bandwidth part (BP) may be a set ofsubbands consecutively positioned in the frequency domain, and cover thesystem band or a designated band (set S). In Table 9, the size of eachsubband, the size of a BP and the number of BPs may depend on the sizeof the system band. In addition, the UE transmits CQIs for respectiveBPs in ascending order in the frequency domain so as to cover the systemband or designated band (set S).

The UE may have the following PUCCH transmission types according to atransmission combination of CQI/PMI/PTI/RI.

i) Type 1: the UE transmits a subband (SB) CQI of Mode 2-0 and Mode 2-1.

ii) Type 1a: the UE transmits an SB CQI and a second PMI.

iii) Types 2, 2b and 2c: the UE transmits a WB-CQI/PMI.

iv) Type 2a: the UE transmits a WB PMI.

v) Type 3: the UE transmits an RI.

vi) Type 4: the UE transmits a WB CQI.

vii) Type 5: the UE transmits an RI and a WB PMI.

viii) Type 6: the UE transmits an RI and a PTI.

When the UE transmits an RI and a WB CQI/PMI, the CQI/PMI aretransmitted in subframes having different periodicities and offsets. Ifthe RI needs to be transmitted in the same subframe as the WB CQI/PMI,the CQI/PMI are not transmitted.

Aperiodic CSI Request

Currently, the LTE standard uses the 2-bit CSI request field in DCIformat 0 or 4 to operate aperiodic CSI feedback when considering acarrier aggregation (CA) environment. When the UE is configured withseveral serving cells in the CA environment, the CSI request field isinterpreted as two bits. If one of the TMs 1 through 9 is set for allCCs (Component Carriers), aperiodic CSI feedback is triggered accordingto the values in Table 8 below, and TM 10 for at least one of the CCs Ifset, aperiodic CSI feedback is triggered according to the values inTable 9 below.

TABLE 8 A value of CSI request field Description ‘00’ No aperiodic CSIreport is triggered ‘01’ Aperiodic CSI report is triggered for a servingcell ‘10’ Aperiodic CSI report is triggered for a first group of servingcells configured by a higher layer ‘11’ Aperiodic CSI report istriggered for a second group of serving cells configured by a higherlayer

TABLE 9 A value of CSI request field Description ‘00’ No aperiodic CSIreport is triggered ‘01’ Aperiodic CSI report is triggered for a CSIprocess group configured by a higher layer for a serving cell ‘10’Aperiodic CSI report is triggered for a first group of CSI processesconfigured by a higher layer ‘11’ Aperiodic CSI report is triggered fora second group of CSI processes configured by a higher layer

The present invention relates to a method of providing a plurality ofdifferent services in a system by applying a different service parameteraccording to a service or a UE to satisfy a requirement of each of aplurality of the services. In particular, the present invention relatesto a method of reducing latency as much as possible by transmitting dataas soon as possible during a short time period using a short TTI(transmission time interval) for a service/UE sensitive to latency andtransmitting a response within short time in response to the data. Onthe contrary, it may transmit and receive data using a longer TTI for aservice/UE less sensitive to the latency. For a service/UE sensitive topower efficiency rather than the latency, it may repetitively transmitdata with the same lower power or transmit data using a lengthened TTI.The present invention proposes a method of transmitting controlinformation and a data signal for enabling the abovementioned operationand a multiplexing method.

For clarity, 1 ms currently used in LTE/LTE-A system is assumed as abasic TTI. A basic system is also based on LTE/LTE-A system. When adifferent service/UE is provided in a base station of LTE/LTE-A systembased on a TTI of 1 ms (i.e., a subframe length), a method oftransmitting a data/control channel having a TTI unit shorter than 1 msis proposed for a service/UE sensitive to latency. In the following, aTTI of 1 ms is referred to as a normal TTI, a TTI of a unit smaller than1 ms (e.g., 0.5 ms) is referred to as a short TTI, and a TTI of a unitlonger than 1 ms (e.g., 2 ms) is referred to as a long TTI.

First of all, a method of supporting a short TTI of a unit shorter than1 ms in a system basically using a normal TTI of 1 ms unit used inlegacy LTE/LTE-A system is described. First of all, downlink (DL) isexplained. Multiplexing between channels having a different TTI size inan eNB and an example of uplink (UL) transmission for the multiplexingare shown in FIG. 5. As a TTI is getting shorter, time taken for a UE tobuffer and decode a control channel and a data channel is gettingshorter. Time taken for performing UL transmission in response to thecontrol channel and the data channel is getting shorter. As shown in theexample of FIG. 5, in case of transmission of 1 ms TTI, when a DLchannel is transmitted in a specific n^(th) subframe, an eNB can receivea response in an (n+4)^(th) subframe in response to the DL channel. Incase of transmission of 0.5 TTI, when a DL channel is transmitted in aspecific n^(th) subframe, an eNB can receive a response in an (n+2)^(th)subframe in response to the DL channel. In particular, in order tosupport TTIs of a different length, it is necessary to support backwardcompatibility to prevent an impact on a UE operating in a legacy systemonly for DL and UL multiplexing of channels having a different TTI.

When DL/UL channels having a different length of TTI are multiplexed, itis necessary to define a method for a UE, which has received thechannels, to read a control channel and transmit/receive a data channelA UE supporting a normal TTI only, a UE supporting a normal TTI and ashort TTI, and a UE supporting a normal TTI, a short TTI, and a long TTImay coexist in a system. In this case, when a UE supports a short TTIand a normal TTI, it means that the UE is able to receive and demodulateboth a channel transmitted with a short TTI (“short TTI channel”) and achannel transmitted with a normal TTI (“normal TTI channel”) and is ableto generate and transmit the short TTI channel and the normal TTIchannel in UL.

In a legacy LTE/LTE-A system, one subframe, i.e., a TTI, has a length of1 ms and one subframe includes two slots. One slot corresponds to 0.5ms. In case of a normal CP, one slot includes 7 OFDM symbols. A PDCCH(physical downlink control channel) is positioned at a forepart of asubframe and is transmitted over the whole band. A PDSCH (physicaldownlink shared channel) is transmitted after the PDCCH. PDSCHs of UEsare multiplexed on a frequency axis after a PDCCH section. In order fora UE to receive PDSCH of the UE, the UE should know a position to whichthe PDSCH is transmitted. Information on the position, MCS information,RS information, antenna information, information on a transmissionscheme, information on a transmission mode (TM), and the like can beobtained via the PDCCH. For clarity, PDCCH having a short TTI and PDSCHhaving a short TTI are referred to as sPDCCH and sPDSCH, respectively.If a UE receives the sPDSCH, the UE transmits HARQ-ACK via a PUCCH(physical uplink control channel) in response to the sPDSCH. In thiscase, a PUCCH having a short TTI is referred to as sPUCCH.

Handling of ACK/NACK (A/N) Overlap Between Different TTIs

It may consider a case that DL channels having a different length of TTIare multiplexed and a UE, which has received the DL channels, transmitsHARQ-ACK feedback in response to the DL channels. Specifically, it mayconsider a case that transmission timing of HARQ-ACK feedback for aPDSCH having a short TTI is overlapped with transmission timing ofHARQ-ACK feedback for a PDSCH having a normal TTI. FIG. 6 illustrates anexample for the case. When a DL channel is transmitted in a specificn^(th) subframe, in case of a normal TTI, an eNB can receive a responsein an (n+4)^(th) subframe in response to the DL channel On the contrary,when a DL channel is transmitted in a specific n^(th) subframe, in caseof a short TTI (e.g., 0.5 ms), an eNB can receive a response in an(n+2)^(th) subframe in response to the DL channel. A case that A/Nshaving a different TTI are overlapped corresponds to an example for casethat a short TTI is the half of a normal/legacy TTI. Yet, the case canalso be applied to a short TTI having a different size.

Referring to [case 1] of FIG. 6, transmission timing of HARQ-ACKfeedback for a PDSCH having a normal TTI is overlapped with transmissiontiming of HARQ-ACK feedback for a PDSCH having a short TTI scheduled ina first slot. Referring to [case 2] of FIG. 6, transmission timing ofHARQ-ACK feedback for a PDSCH having a normal TTI is overlapped withtransmission timing of HARQ-ACK feedback for a PDSCH having a short TTIscheduled in a second slot. Referring to [case 3] of FIG. 6,transmission timing of HARQ-ACK feedback for a PDSCH having a normal TTIis overlapped with transmission timing of HARQ-ACK feedbacks for twoPDSCHs having a short TTI scheduled in a second slot. In particular, iftransmission timings of HARQ-ACK feedbacks, which are transmitted inresponse to DL channels of a different length of TTI, are overlapped, itis necessary for a UE to have a method for efficiently transmitting theHARQ-ACK feedback. In general, when a short TTI corresponds to 1/n of anormal/legacy TTI, the method can be applied to cases that HARQ-ACKfeedback for a PDSCH transmitted with one or a plurality of short TTIsamong the n number of short TTIs is overlapped with HARQ-ACK feedbacktransmitted with a normal TTI (or, a long TTI).

According to one embodiment of the present invention, if transmissiontimings of a plurality of HARQ-ACK feedbacks having a different TTI areoverlapped, a UE can transmit A/N information via sPUCCH having a shortTTI. In the following, a method of transmitting sPUCCH configured by aplurality of HARQ-ACK feedbacks is explained.

(1) Regarding Transmission Timing

A. If transmission timings for a plurality of HARQ-ACK feedbacks havinga different TTI are overlapped, a plurality of the HARQ-ACK feedbacksare transmitted at HARQ-ACK feedback transmission timing having ashortest TTI carried on sPUCCH together. For example, referring to thecase 1, short TTI A/N information and normal TTI ACK/NACK informationare transmitted together via sPUCCH in a first slot of SF # n+4.Referring to the case 2, short TTI A/N information and normal TTI A/Ninformation are transmitted together via sPUCCH in a second slot of SF #n+4. Referring to the case 3, short TTI A/N 1 information and normal TTIA/N information are transmitted together via sPUCCH in a first slot ofSF # n+4 and short TTI A/N 2 information and normal TTI A/N informationare transmitted together via sPUCCH in a second slot of SF # n+4. Incase of the case 3, since the normal TTI A/N information is transmittedtogether with the short TTI A/N information 1 and the short TTI A/Ninformation 2 (i.e., repetition), it may be able to increasereliability.

B. If transmission timings for a plurality of HARQ-ACK feedbacks havinga different TTI are overlapped, a plurality of the HARQ-ACK feedbackscan be transmitted in a manner of being carried on PUCCH/sPUCCH ofHARQ-ACK feedback transmission timing having a predefined (or, signaled)TTI.

C. Similar to the case 3, if transmission timings for HARQ-ACK feedbackshaving a plurality of short TTIs are overlapped during a time periodcorresponding to a normal TTI, it may be able to define a rule thatnormal TTI A/N information is to be transmitted on sPUCCH ofpredefined/promised timing (or, timing designated via signaling).

(2) Regarding Transmission Resource

A. It may be able to define a rule that a transmission resource ofsPUCCH including short TTI A/N information and normal (or long) TTI A/Ninformation is to be linked with a CCE index of a DL grant controlchannel (i.e., PDCCH or EPDCCH) that schedules a corresponding short TTIA/N target PDSCH. Or, it may indicate that a short TTI A/N resource isused. Or, it may use a normal (or long) TTI A/N resource. In particular,when A/N resources for a DL channel transmission of a length of two ormore TTIs are overlapped and are not overlapped, it may indicate thatresource selection for at least one TTI is used.

B. It may be able to define a rule that (a plurality of) resources forsPUCCH are defined/configured in advance via a higher layer signal andone of the resources is to be indicated via a specific field (e.g., aTPC (transmission power control)/ARI (ack/nack resource indicator)field) included in a DL grant control channel (i.e., PDCCH or EPDCCH)scheduling a short TTI A/N target PDSCH to indicate a resource in whichthe sPUCCH is transmitted. A method of designating a transmissionresource can be applied only when a collision occurs between A/Nresources. Or, the method can also be applied even when there is nocollision. In particular, in order to solve a collision issue, it may beable to introduce an indicator to dynamically change an A/N resource.

C. If transmission timings of a plurality of HARQ-ACK feedbacks having adifferent TTI are overlapped, an eNB can determine a transmission methodfrom among a channel selection method and a PUCCH format 3 (or a newPUCCH format) in advance. Or, if TTIs are overlapped, it mayunconditionally apply bundling. The bundling can be applied according toa codeword (same codeword of two TTIs). Or, if one or more codewordsexist according to a TTI, it may apply the bundling between thecodewords according to a TTI. In case of the former method, when A/N foreach TTI is 1 bit and there is a single codeword, A/N of 1 bit isgenerated. On the contrary, in case of the latter method, since A/N bitof 1 bit is generated according to a TTI, at least two bits are alwaysrequired. More generally, if A/N bit according to a TTI is equal to orgreater than 1 bit (e.g., A/N transmitted over a plurality of subframesof TDD), A/N is processed according to a TTI and the A/N can betransmitted using a PUCCH format 3 or a channel selection method.

D. If DL channels of a different TTI rotate without MIMO transmission,each of short TTI A/N information and normal (or long) TTI A/Ninformation is regarded as a single codeword and A/N transmission fortwo TTIs can be performed. A part corresponding to a normal (or long)TTI can be handled as a first codeword and a part corresponding to ashort TTI can be handled as a second codeword, and vice versa. In thiscase, if one or more codewords are transmitted within a single TTI, itmay assume that bundling is preferentially performed between thecodewords.

According to a different embodiment of the present invention, iftransmission timings of a plurality of HARQ-ACK feedbacks having adifferent TTI are overlapped, a UE can transmit corresponding A/Ninformation via a legacy PUCCH having a normal TTI. In the following, amethod of transmitting sPUCCH configured by a plurality of HARQ-ACKfeedbacks is explained in detail. Although options described in thefollowing are explained with an example of a PUCCH format 3, by whichthe present invention may be non-limited. It is apparent that it is ableto apply the options to a different UL control channel as well.

(1) Option 1: If transmission timings of a plurality of HARQ-ACKfeedbacks having a different TTI are overlapped, a UE can transmitcorresponding A/N information using a PUCCH format 3 having a normalTTI. In this case, a payload of the PUCCH format 3 configures normal TTIA/N information only and it may be able to represent as short TTI A/Ninformation applies an OCC (orthogonal cover code) (e.g., +1, +1 or +1,−1) between DMRSs in each slot constructing the PUCCH format 3. FIG. 7illustrates a detail example of the option 1.

(2) Option 2: If transmission timings of a plurality of HARQ-ACKfeedbacks having a different TTI are overlapped, a UE can transmitcorresponding A/N information using a PUCCH format 3 having a normalTTI. In this case, a payload of the PUCCH format 3 configures long TTIA/N information only and short TTI A/N information can be represented bya channel selection method. FIG. 8 illustrates a detail example of theoption 2.

According to a further different embodiment of the present invention, iftransmission timings of a plurality of HARQ-ACK feedbacks having adifferent TTI are overlapped, it may be able to define/promise a channelto be used in advance among sPUCCH having a short TTI and a legacy PUCCHhaving a normal TTI. Or, it may be able to define a rule that an eNBconfigures a channel to be used among sPUCCH having a short TTI and alegacy PUCCH having a normal TTI via higher layer signaling or physicallayer signaling.

Or, it may be able to determine a channel to be used among sPUCCH havinga short TTI and a legacy PUCCH having a normal TTI according to a totalpayload size of UCI (uplink control information) or a coding rate of theUCI without any separate configuration.

According to a further different embodiment of the present invention,A/N transmissions as many as a specific number can be dropped only whentransmission timings of a plurality of HARQ-ACK feedbacks having adifferent TTI are overlapped. A/N transmission to be dropped can beconfigured by a network. A higher priority can be provided to aretransmission. Or, the determination may vary depending on power of aUE. For example, if power for transmitting a single TTI already arrivesat PCmax, c, since it is unable to increase power for increasing A/Nbit, the remaining A/N can be dropped or unconditional bundling can beperformed.

According to a further different embodiment of the present invention, iftransmission timings of a plurality of HARQ-ACK feedbacks having adifferent TTI are overlapped, a UE can perform transmission bydifferently applying an aggregation/bundling method of A/N according toUL transmit power.

In case of transmitting A/N by aggregating/bundling the A/N via theaforementioned scheme, A/N can be dropped or bundled in a single TTIonly when power according to newly transmitted A/N is higher than PCmax,c, or power is restricted due to carrier aggregation (CA) or the like.In particular, if transmit power is sufficient enough, A/N of many bitsis transmitted via a PUCCH format 3 or a channel selection method. Ifthere is a restriction on transmit power, a plurality of A/N can bebundled or one of a plurality of A/N can be dropped. In general, if aconfiguration of A/N bit is changed, it is necessary to reconfiguredynamically allocated power as well in consideration of a TPC loopoperating in accordance with a short/normal TTI. In particular, itindicates that an actual transmit power configuration is configuredaccording to a short TTI, a normal TTI, or the number of transmitted A/Nbits.

According to a further different embodiment of the present invention, iftransmission timings of a plurality of HARQ-ACK feedbacks having adifferent TTI are overlapped, a UE regards normal TTI A/N and short TTIA/N as A/N information of a Pcell and A/N information of a Scell,respectively. Or, the UE regards short TTI A/N and normal TTI A/N as A/Ninformation of a Pcell and A/N information of a Scell, respectively.Then, the UE can transmit A/N information by mapping the informationaccording to a legacy channel selection method.

For example, it may assume that A/N timing of a short TTI corresponds toPcell timing. And, it may assume that A/N timing of a normal TTI or adifferent TTI corresponds to Scell timing. In order to transmit the A/N,a UE may assume that Pcell and Scell are aggregated each other. On thecontrary, it may assume that A/N timing of a normal TTI or a differentTTI corresponds to Pcell timing. In case of the former case, it mayassume that A/N is transmitted according to the timing of the short TTI.In case of the latter case, it may assume the A/N is transmittedaccording to the timing of the normal TTI. In case of using the lattercase, a plurality of A/N of a short TTI can be overlapped with PUCCHtransmission timing of a normal TTI. In this case, it may be able toperform aggregation or bundling. In this case, it may follow a resourceselection method and a PUCCH format in carrier aggregation (CA).

Handling of A/N and CQI Overlap Between Different TTIs

According to a further different embodiment of the present invention, iftransmission timing of HARQ-ACK feedback having a different TTI isoverlapped with transmission timing of CQI feedback, it is necessary toefficiently utilize a resource. If transmission timing of HARQ-ACKfeedback having a different TTI is overlapped with transmission timingof CQI feedback, it may consider multiplexing methods described in thefollowing.

(1) Option 1: If transmission timing of HARQ-ACK feedback having a shortTTI is overlapped with transmission timing of CQI having a normal TTI, aUE transmits corresponding information by multiplexing the informationvia a legacy PUCCH having a normal TTI. In this case, a payload of aPUCCH format 2/2a/2b/3 (or, a newly defined PUCCH format) is configuredby CQI feedback information only and short TTI A/N information can berepresented by applying an OCC between DMRSs. Or, the short TTI A/Ninformation can be represented by a channel selection method.

(2) Option 2: If transmission timing of HARQ-ACK feedback having anormal TTI is overlapped with transmission timing of CQI having a shortTTI, a UE transmits corresponding information by multiplexing theinformation via sPUCCH having a short TTI. In this case, a payload ofthe sPUCCH is configured by CQI feedback information only and normal TTIA/N information can be represented by applying an OCC between DMRSs. Or,the normal TTI A/N information can be represented by a channel selectionmethod.

Resource Allocation of sPUCCH

According to LTE standard, a legacy PUCCH has considered slot hopping toobtain a frequency diversity gain. Yet, if a length of a short TTI isconfigured by 0.5 ms or time shorter than 0.5 ms, it may be difficult toconsider the legacy slot hopping within the TTI in designing sPUCCH.Meanwhile, if the legacy PUCCH is mapped to a resource of a PRB index 0in a first slot, the legacy PUCCH is automatically mapped to a resourceof a PRB index (N_(RB) ^(UL-1)) in a second slot. However, if thehopping (i.e., PUCCH hopping within TTI) is introduced to a short TTI,it may wrongly set a limit on the legacy PUCCH. Hence, it is preferablethat a sPUCCH resource does not perform hopping within a TTI. Forexample, if sPUCCH having a short TTI is mapped to a resource of a PRBindex 0 of a first slot, it may be able to make the legacy PUCCH not tobe mapped to a resource of a PRB index (N_(RB) ^(UL-1)) of a secondslot.

In particular, if a resource of sPUCCH has a short TTI, the resource canbe mapped to a specific PRB index during a time period of apredetermined length (i.e., a time period corresponding to thepredetermined number of TTIs). And/or, the resource can be mapped to adifferent specific PRB index during the remaining time. In particular,it may be able to expect an effect that the resource of the sPUCCH ismapped to the same resource to which slot hopping of a normal TTI isapplied. Specifically, if a length of a short TTI is configured by 0.5ms, it may be able to define a rule that sPUCCH is mapped to a differentphysical resource in every TTI (i.e., 0.5 ms).

In particular, in case of a short TTI, a resource index, which is mappedaccording to a TTI index, corresponds to a virtual index rather than aphysical index. A function for mapping a virtual index to a physicalindex can be defined according to each TTI. By doing so, it may be ableto make a legacy PUCCH resource or a PUCCH resource of a long TTI to bemultiplexed with a PUCCH resource of a short TTI.

As a different example, if a length of a short TTI is configured by 1SC-FDMA symbol, it may be able to define a rule that sPUCCH is mapped tothe same physical resource during 7 TTIs and is mapped to a differentphysical resource during next 7 TTIs. The rule can be applied to apredetermined (or, signaled) specific PUCCH format only.

In particular, if sPUCCH hopping within a TTI is not supported, it maycause a problem of decreasing coverage of a control channel. In order tosolve the problem, a UE can repetitively transmit a specific sPUCCHduring the (predetermined or signaled) specific number of TTIs. A methodof repetitively transmitting sPUCCH is described in the following indetail.

(1) It may be able to define a rule that an eNB allows a UE to repeatsPUCCH via higher layer (or, physical layer) signaling. When sPUCCHrepetition is allowed, the eNB can configure the number of TTIs at whicha repetition part of the sPUCCH is transmitted, the number of TTIsduring which the repetition part of the sPUCCH is transmitted, detailinformation on a resource in which the repetition part of the sPUCCH isto be transmitted, information on whether to follow legacy resourcemapping, information on whether or not the repetition part of the sPUCCHis transmitted in a separate resource, and the like via higher layersignaling or physical layer signaling.

(2) In order to make a UE transmit a repetition part of sPUCCH at aspecific TTI, it may be able to define a rule that transmission of therepetition part is allowed only when there is no sPUCCH to be newlytransmitted at the TTI.

(3) If transmission timing of a repetition part of sPUCCH is overlappedwith transmission timing of a new sPUCCH, it may be able to define arule that the repetition part of the sPUCCH and the new sPUCCH aretransmitted on a single sPUCCH by bundling the repetition part of thesPUCCH with the new sPUCCH. In this case, the sPUCCH can be transmittedby a predetermined resource or a resource indicated by higherlayer/physical layer signaling among (predetermined/signaled separate)resources in which the new sPUCCH or the repetition part is to betransmitted.

(4) If transmission timing of a repetition part of sPUCCH is overlappedwith transmission timing of a new sPUCCH, it may be able to define arule that the new sPUCCH is to be transmitted at a next TTI. Iftransmission timing of the new sPUCCH, which is delayed as much as 1TTI, is overlapped with transmission timing of a different sPUCCH, itmay be able to define a rule that the new sPUCCH and the differentsPUCCH are to be transmitted on a single sPUCCH by bundling the newsPUCCH with the different sPUCCH. In this case, the sPUCCH can betransmitted by a predetermined resource or a resource indicated byhigher layer/physical layer signaling among (predetermined/signaledseparate) resources in which the delayed new sPUCCH or the differentsPUCCH is to be transmitted. FIG. 9 illustrates a specific example forthe abovementioned rule.

FIG. 10 is a flowchart for an operation according to one embodiment ofthe present invention.

FIG. 10 illustrates a method of transmitting an uplink control channelfor a UE configured to support multiple TTI (transmission time interval)lengths in a wireless communication system. The method is performed bythe UE.

The UE may receive a first PDSCH (physical downlink shared channel)based on a first TTI length from an eNB at first timing [S1010]. The UEmay receive a second PDSCH based on a second TTI length different fromthe first TTI length from the eNB at second timing [S1020].

When a TTI for transmitting an uplink control channel for the firstPDSCH is overlapped with a TTI for transmitting an uplink controlchannel for the second PDSCH, the UE may transmit uplink controlinformation for the first PDSCH and the second PDSCH to the eNB on aPUCCH (physical uplink control channel) having a shorter TTI lengthamong the first TTI length and the second TTI length [S1030].

In this case, the PUCCH may be transmitted in a shorter TTI among theTTI for transmitting the uplink control channel for the first PDSCH andthe TTI for transmitting the uplink control channel for the secondPDSCH. Or, the PUCCH may n be transmitted in a TTI for transmitting apredetermined uplink control channel.

When a TTI for transmitting an uplink control channel for a third PDSCHis overlapped with the TTI for transmitting the uplink control channelfor the first and the second PDSCH, the UE may transmit an uplinkcontrol channel for a PDSCH based on a longest TTI among the firstPDSCH, the second PDSCH, and the third PDSCH or a PDSCH based on a TTIlength having a length of 1 ms in a TTI for transmitting a predetermineduplink control channel.

The PUCCH may be linked to a CCE (control channel element) index of aPDCCH (physical downlink control channel) that schedules PDSCH based ona shorter TTI length among a length of the first TTI and a length of thesecond TTI. Or, the PUCCH can be determined by the CCE index.

Or, the PUCCH may be indicated by a PDCCH that schedules PDSCH based ona shorter TTI length among the length of the first TTI and the length ofthe second TTI among a plurality of predetermined PUCCHs.

When a TTI for transmitting an uplink control channel for the firstPDSCH is overlapped with a TTI for transmitting an uplink controlchannel for the second PDSCH, uplink control information for the firstPDSCH and the second PDSCH may be transmitted by one selected from thegroup consisting of a channel selection method, a new PUCCH format, andbundling.

When hopping of the PUCCH is not allowed within a TTI corresponding tothe shorter TTI length, the UE may receive a configuration on whether ornot the repetitive transmission of the PUCCH is allowed from the eNB.When the repetitive transmission of the PUCCH is allowed, the UE mayreceive configuration information including at least one selected fromthe group consisting of a TTI in which a repetition part of the PUCCH istransmitted, a TTI section during which the repetition part of the PUCCHis transmitted, an uplink resource in which the repetition part of thePUCCH is transmitted, and criteria for determining the uplink resourcein which the repetition part of the PUCCH is transmitted from the eNB.

In the foregoing description, embodiments of the present invention havebeen briefly explained with reference to FIG. 10. An embodiment relatedto FIG. 10 can alternatively or additionally include at least a part ofthe aforementioned embodiments.

Since it is able to include the examples for the proposed method as oneof implementation methods of the present invention, it is apparent thatthe examples are considered as a sort of proposed methods. Although theembodiments of the present invention can be independently implemented,the embodiments can also be implemented in a combined/aggregated form ofa part of embodiments. It may define a rule that an eNB/location serverinforms a UE of information on whether to apply the proposed methods(or, information on rules of the proposed methods) via a predefinedsignal (e.g., physical layer signal or higher layer signal).

FIG. 11 is a block diagram illustrating a transmitting device 10 and areceiving device 20 configured to implement embodiments of the presentinvention. Each of the transmitting device 10 and receiving device 20includes a transmitter/receiver 13, 23 capable of transmitting orreceiving a radio signal that carries information and/or data, a signal,a message, etc., a memory 12, 22 configured to store various kinds ofinformation related to communication with a wireless communicationsystem, and a processor 11, 21 operatively connected to elements such asthe transmitter/receiver 13, 23 and the memory 12, 22 to control thememory 12, 22 and/or the transmitter/receiver 13, 23 to allow the deviceto implement at least one of the embodiments of the present inventiondescribed above.

The memory 12, 22 may store a program for processing and controlling theprocessor 11, 21, and temporarily store input/output information. Thememory 12, 22 may also be utilized as a buffer. The processor 11, 21controls overall operations of various modules in the transmittingdevice or the receiving device. Particularly, the processor 11, 21 mayperform various control functions for implementation of the presentinvention. The processors 11 and 21 may be referred to as controllers,microcontrollers, microprocessors, microcomputers, or the like. Theprocessors 11 and 21 may be achieved by hardware, firmware, software, ora combination thereof. In a hardware configuration for an embodiment ofthe present invention, the processor 11, 21 may be provided withapplication specific integrated circuits (ASICs) or digital signalprocessors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), and field programmable gate arrays(FPGAs) that are configured to implement the present invention. In thecase which the present invention is implemented using firmware orsoftware, the firmware or software may be provided with a module, aprocedure, a function, or the like which performs the functions oroperations of the present invention. The firmware or software configuredto implement the present invention may be provided in the processor 11,21 or stored in the memory 12, 22 to be driven by the processor 11, 21.

The processor 11 of the transmitter 10 performs predetermined coding andmodulation of a signal and/or data scheduled by the processor 11 or ascheduler connected to the processor 11, and then transmits a signaland/or data to the transmitter/receiver 13. For example, the processor11 converts a data sequence to be transmitted into K layers throughdemultiplexing and channel coding, scrambling, and modulation. The codeddata sequence is referred to as a codeword, and is equivalent to atransport block which is a data block provided by the MAC layer. Onetransport block is coded as one codeword, and each codeword istransmitted to the receiving device in the form of one or more layers.To perform frequency-up transformation, the transmitter/receiver 13 mayinclude an oscillator. The transmitter/receiver 13 may include Nttransmit antennas (wherein Nt is a positive integer greater than orequal to 1).

The signal processing procedure in the receiving device 20 is configuredas a reverse procedure of the signal processing procedure in thetransmitting device 10. The transmitter/receiver 23 of the receivingdevice 20 receives a radio signal transmitted from the transmittingdevice 10 under control of the processor 21. The transmitter/receiver 23may include Nr receive antennas, and retrieves baseband signals byfrequency down-converting the signals received through the receiveantennas. The transmitter/receiver 23 may include an oscillator toperform frequency down-converting. The processor 21 may perform decodingand demodulation on the radio signal received through the receiveantennas, thereby retrieving data that the transmitting device 10 hasoriginally intended to transmit.

The transmitter/receiver 13, 23 includes one or more antennas. Accordingto an embodiment of the present invention, the antennas function totransmit signals processed by the transmitter/receiver 13, 23 are toreceive radio signals and deliver the same to the transmitter/receiver13, 23. The antennas are also called antenna ports. Each antenna maycorrespond to one physical antenna or be configured by a combination oftwo or more physical antenna elements. A signal transmitted through eachantenna cannot be decomposed by the receiving device 20 anymore. Areference signal (RS) transmitted in accordance with a correspondingantenna defines an antenna from the perspective of the receiving device20, enables the receiving device 20 to perform channel estimation on theantenna irrespective of whether the channel is a single radio channelfrom one physical antenna or a composite channel from a plurality ofphysical antenna elements including the antenna. That is, an antenna isdefined such that a channel for delivering a symbol on the antenna isderived from a channel for delivering another symbol on the sameantenna. An transmitter/receiver supporting the Multiple-InputMultiple-Output (MIMO) for transmitting and receiving data using aplurality of antennas may be connected to two or more antennas.

In embodiments of the present invention, the UE or the terminal operatesas the transmitting device 10 on uplink, and operates as the receivingdevice 20 on downlink. In embodiments of the present invention, the eNBor the base station operates as the receiving device 20 on uplink, andoperates as the transmitting device 10 on downlink.

The transmitting device and/or receiving device may be implemented byone or more embodiments of the present invention among the embodimentsdescribed above.

Detailed descriptions of preferred embodiments of the present inventionhave been given to allow those skilled in the art to implement andpractice the present invention. Although descriptions have been given ofthe preferred embodiments of the present invention, it will be apparentto those skilled in the art that various modifications and variationscan be made in the present invention defined in the appended claims.Thus, the present invention is not intended to be limited to theembodiments described herein, but is intended to have the widest scopeconsistent with the principles and novel features disclosed herein.

INDUSTRIAL APPLICABILITY

The present invention is applicable to wireless communication devicessuch as a terminal, a relay, and a base station.

What is claimed is:
 1. A method of transmitting an uplink controlchannel by a terminal in a wireless communication system, the methodcomprising: receiving a first physical downlink shared channel (PDSCH)based on a first transmission time interval (TTI) length; receiving asecond PDSCH based on a second TTI length different from the first TTIlength; and transmitting a first hybrid automatic repeat requestacknowledgment (HARQ-ACK) feedback for the first PDSCH and a secondHARQ-ACK feedback for the second PDSCH, wherein, when a time fortransmission of the first HARQ-ACK feedback and a time for transmissionof the second HARQ-ACK feedback overlap in a time domain, the firstHARQ-ACK feedback and the second HARQ-ACK feedback are transmitted on aphysical uplink control channel (PUCCH) with the first TTI length or thesecond TTI length, whichever is the shorter TTI length.
 2. The method ofclaim 1, further comprising: receiving a first physical downlink controlchannel (PDCCH) that schedules the first PDSCH based on the first TTIlength; and receiving a second PDCCH that schedules the second PDSCHbased on the second TTI length, wherein, when the time for transmissionof the first HARQ-ACK feedback and the time for transmission of thesecond HARQ-ACK feedback overlap in the time domain, a resource of thePUCCH is determined based on the first PDCCH or the second PDCCH,whichever schedules a PDSCH based on the shorter TTI length.
 3. Themethod of claim 1, wherein, when the time for transmission of the firstHARQ-ACK feedback and the time for transmission of the second HARQ-ACKfeedback overlap in the time domain, the first HARQ-ACK feedback and thesecond HARQ-ACK feedback are transmitted on the PUCCH by using HARQ-ACKbundling.
 4. The method of claim 3, wherein the HARQ-ACK bundling isperformed for HARQ-ACKs for codewords based on the first TTI length. 5.The method of claim 3, wherein the HARQ-ACK bundling is performed forHARQ-ACKs for codewords based on the second TTI length.
 6. The method ofclaim 1, further comprising: receiving a third PDSCH based on a thirdTTI length different from the first and second TTI lengths; andtransmitting a third HARQ-ACK for the third PDSCH, wherein, when thetime for transmission of the first HARQ-ACK feedback, the time fortransmission of the second HARQ-ACK feedback and a time for transmissionof the third HARQ-ACK feedback overlap in the time domain, the firstHARQ-ACK feedback, the second HARQ-ACK feedback and the third HARQ-ACKfeedback are transmitted on a PUCCH with the first TTI length, thesecond TTI length or the third TTI length, whichever is the shortest TTIlength.
 7. An apparatus for controlling transmission of an uplinkcontrol channel in wireless communication system, the apparatuscomprising: a processor; and a memory that is operably connectable tothe processor and that has stored thereon instructions which, whenexecuted, cause the processor to perform operations comprising:controlling a receiver to receive a first physical downlink sharedchannel (PDSCH) based on a first transmission time interval (TTI)length; controlling the receiver to receive a second PDSCH based on asecond TTI length different from the first TTI length; and controlling atransmitter to transmit a first hybrid automatic repeat requestacknowledgment (HARQ-ACK) feedback for the first PDSCH and a secondHARQ-ACK feedback for the second PDSCH, wherein when a time fortransmission of the first HARQ-ACK feedback and a time for transmissionof the second HARQ-ACK feedback overlap in a time domain, the firstHARQ-ACK feedback and the second HARQ-ACK feedback are transmitted on aphysical uplink control channel (PUCCH) with the first TTI length or thesecond TTI length, whichever is the shorter TTI length.
 8. The apparatusof claim 7, wherein the operations further comprise: controlling thereceiver to receive a first physical downlink control channel (PDCCH)that schedules the first PDSCH based on the first TTI length; andcontrolling the receiver to receive a second PDCCH that schedules thesecond PDSCH based on the second TTI length, wherein, when the time fortransmission of the first HARQ-ACK feedback and the time fortransmission of the second HARQ-ACK feedback, a resource of the PUCCH isdetermined based on the first PDCCH or the second PDCCH, whicheverschedules a PDSCH based on the shorter TTI length.
 9. The apparatus ofclaim 7, wherein the operations further comprise: when the time fortransmission of the first HARQ-ACK feedback and the time fortransmission of the second HARQ-ACK feedback overlap in the time domain,the first HARQ-ACK feedback and the second HARQ-ACK feedback aretransmitted on the PUCCH by using HARQ-ACK bundling.
 10. The apparatusof claim 9, wherein the HARQ-ACK bundling is performed for HARQ-ACKs forcodewords based on the first TTI length.
 11. The apparatus of claim 9,wherein the HARQ-ACK bundling is performed for HARQ-ACKs for codewordsbased on the second TTI length.
 12. The apparatus of claim 7, whereinthe operations further comprise: controlling the receiver to receive athird PDSCH based on a third TTI length different from the first andsecond TTI lengths; and controlling the transceiver to transmit a thirdHARQ-ACK for the third PDSCH, wherein, when the time for transmission ofthe first HARQ-ACK feedback, the time for transmission of the secondHARQ-ACK feedback and a time for transmission of the third HARQ-ACKfeedback overlap in the time domain, the first HARQ-ACK feedback, thesecond HARQ-ACK feedback and the third HARQ-ACK feedback are transmittedon a PUCCH with the first TTI length, the second TTI length or the thirdTTI length, whichever is the shortest TTI length.
 13. The apparatus ofclaim 7, wherein the receiver and the transmitter are a receiver of aterminal and a transmitter of the terminal, respectively, to which theapparatus is operatively connectable.
 14. A method of receiving anuplink control channel by a base station in a wireless communicationsystem, the method comprising: transmitting a first physical downlinkshared channel (PDSCH) based on a first transmission time interval (TTI)length to a terminal; transmitting a second PDSCH based on a second TTIlength different from the first TTI length to the terminal; andreceiving a first hybrid automatic repeat request acknowledgment(HARQ-ACK) feedback for the first PDSCH and a second HARQ-ACK feedbackfor the second PDSCH from the terminal, wherein, when a time fortransmission of the first HARQ-ACK feedback and a time for transmissionof the second HARQ-ACK feedback overlap in a time domain, the firstHARQ-ACK feedback and the second HARQ-ACK feedback are received on aphysical uplink control channel (PUCCH) with the first TTI length or thesecond TTI length, whichever is the shorter TTI length.
 15. The methodof claim 14, further comprising: transmitting a first physical downlinkcontrol channel (PDCCH) that schedules the first PDSCH based on thefirst TTI length to the terminal; and transmitting a second PDCCH thatschedules the second PDSCH based on the second TTI length to theterminal, wherein, when the time for transmission of the first HARQ-ACKfeedback and the time for transmission of the second HARQ-ACK feedbackoverlap in the time domain, a resource of the PUCCH is determined basedon the first PDCCH or the second PDCCH, whichever schedules a PDSCHbased on the shorter TTI length.
 16. The method of claim 14, wherein,when the time for transmission of the first HARQ-ACK feedback and thetime for transmission of the second HARQ-ACK feedback overlap in thetime domain, the PUCCH carries HARQ-ACK bits for the first HARQ-ACKfeedback and the second HARQ-ACK feedback by using HARQ-ACK bundling.17. The method of claim 16, wherein at least one of the HARQ-ACK bits isa bundled HARQ-ACK bit for codewords based on the first TTI length. 18.The method of claim 16, wherein at least one of the HARQ-ACK bits is abundled HARQ-ACK for codewords based on the second TTI length.
 19. Themethod of claim 14, further comprising: transmitting a third PDSCH basedon a third TTI length different from the first and second TTI lengths,to the terminal; and receiving a third HARQ-ACK for the third PDSCH tothe terminal, wherein, when the time for transmission of the firstHARQ-ACK feedback, the time for transmission of the second HARQ-ACKfeedback and a time for transmission of the third HARQ-ACK feedbackoverlap in the time domain, the first HARQ-ACK feedback, the secondHARQ-ACK feedback and the third HARQ-ACK feedback are received on aPUCCH with the first TTI length, the second TTI length or the third TTIlength, whichever is the shortest TTI length.